package MyClass; use base qw(Class::Tangram); our $fields = { int => [ qw(a b c d e) ] }; sub set_b { my $self = shift; my $new_b = shift; $self->SUPER::set_b($new_b + 3); } package main; my $foo = MyClass->new( a => 1, b => 2 ); print $foo->a; # prints 1 print $foo->b; # prints 5